Fix a bug preventing ClassSource.retry() from working correctly.

We returned the class of the other ClassSource, instead of invoking
its loadClass() method.

ProtocolLib/src/main/java/com/comphenix/protocol/utility/ClassSource.java

@@ -64,7 +64,7 @@ public abstract class ClassSource {
 				try {
 					return ClassSource.this.loadClass(canonicalName);
 				} catch (ClassNotFoundException e) {
-					return other.getClass();
+					return other.loadClass(canonicalName);
 				}
 			}
 		};